John h



J. H. WHEELOCK.

SOUND PRODUCER.

APPLICATION HLED JULY I8, 1917.

1,312,373. Patented Aug. 5,1913).

11 I 4 Z6 Z1 27 W i W UNITED STATES PATE JOHN H. WHEELOCK, OF WORCESTER, MASSACHUSETTS, ASSIGNOR'TO KLAXON COM- PANY, OF NEWARK, NEW JERSEY, A CORPORATION OF DELAWARE.

SOUND-PRODUCER.

Application filed July 18 1917. Serial No. 181,194.

. a single rod or plunger. The latter. is preferably actuated by an electro-magn'et energized by suitably varying currents, prefer-v ably by alternatlng currents, though fluctuating or interrupted currents may be employed.

One object of the invention is to provide exceedingly simple mechanism having no parts likely to get out of order or out of place under conditions of practical use.'

Another object is to provide a two-diaphragm horn having a single intermediate actuator, these three moving elements being coordinated and arranged so as to vibrate in the greatest possible mechanical harmony and efficiency and with the least possible mechanical or acoustical interference. Reference is to be had to the accompanying drawings, in which Figure 1 is an elevation of a double horn constructed in accordance with this invention with parts in section to show the operating mechanism inside, and i Fig. 2 is a transverse sectional view of the line 2-2 of Fig. 1.

In the form of the invention shown two horns 10 of any usual construction areprovided and a cylindrical casing 11 which may be formed of cast or pressed metal. This casing is provided with a substantially flat end 12 which has a flat-topped circumferential ridge 13 to provide a space for a sounding diaphragm 14,

Extending across the casing is shown a diametrical integral solid' cross piece 16 designed to support .the operative mechanism inside. At the other end the casing 11 is pcpvided with a second flat circumferential r1 e Th se two diaphragms 14 and 19 are thus arranged in.parallel relation to each other and located substantially at the ends of the casing, each of them communicating directly with a horn. The diaphragms are pref Specification of Letters Patent.

13 on which is a second diaphragm 19..

Patented Aug. 5, 1919.

erably substantially identical in size, thickness, material and peripheral clamping. Adjustmg screws 15 are employed to control .the tension and tone of the diaphragms.

In this form there is an electro-magnet compr1s1ng two coils 20 each provided with a fixed steel or soft iron core 21 which is headed over on the inside preferably, so that the 0011s are firmly secured to the cross piece 16. The usual wires are shown for connection of the eleotro-magnet with a .source of sultably varying electric currents,

preferably the alternating current source dlagrammatically indicated at G, Fig. 2.

In addition to these features, the cross piece 16 is provided with a guide perforation 24. Extending through this perforation is a plunger 25, one end of which is fixedly connected'with a softiron armature 26. The two ends of the plunger are a suflicient distance apart to abut at all times against the two diaphragms so as always to engage both of them at thesaine time and move back and forth with them.

The operation of the device is very simple. When the current is operating to magnetize the cores, the armature will be attracted in such a direction as to cause the plunger to force out one diaphragm as for example the diaphragm 19. The immediate effect of this is to distort the diaphragm, spring it away from the core, and its'reaction throws the plunger back and distorts the diaphragm 14 while the cores are demagnetized during the alternation of the current. Then the diaphragm 14 reacts and startsthe plunger in the opposite direction, the re-magnetization of the cores assist- "ing in its outward thrust on the diaphragm synchronism of action of all three elements alternating circuit of say cycles per second, the current flowing in one direction for a half cycle and then in the other direction for a half cycle, operates to energize the magnet at the rate of 120 magnetizations per second with intermediate stages of little or no magnetization when the current is decreasing to zero and reversing its direction.

The armature 0n the plunger will therefore be attracted by the magnets 120 times per second thereby causing 120 one-direction forcing movements of the plunger, the 120 intervals of reversing magnetism permitting free elastic return movements or swings back to and beyond the normal position of rest. Hence, in order to obtain the best results, the vibratory systems including the two diaphragms and the intermediate plunger, should be selected and adjusted so as to have a natural time period of approximately 120 complete to and fro swings per second. When this is done, the succession of onedirection pulls ope-rates cumulatively to increase the extent or amplitude of the swings without changing their number per second and without any tendency of the diaphragms to get out of step with each other or with the plunger.

When the diaphragms are in full swing, the plunger operates as a load, first on one diaphragm and then on the other, during the inward, resilient part of the swing, and it will be noticed that when the diaphragms are normally bowed inward by the peripheral clamps or by the screws 15, 15, as indicated in the drawing, the resilient power of the diaphragm will be greatest at the instant when it is most needed. Moreover, at that same instant, the other diaphragm, the one which is free from the load, will be in its position of least resilience. In other words, when thus arranged, the first part of the inward movement of the diaphragm when it must assist in propelling the plunger, is

more powerful than the first part of the outward movement when it is not carrying .the plunger as a load.

The inltial outward bowing of both diaphragms by the plunger acting as a thrust member between them may be and preferably is great enough so that the spring pressure of bothdiaphragms on opposite ends of the plunger is never wholly relaxed, not even at the innermost point of the most violent swings.

-to a point where neither diaphragm ever While these conditions may be perfected same direction at the same time, that is, substantially without mechanical interference. This condition may be easily determined by listening to the sound produced. Loud, clear, non-interfering notes proceeding from both diaphragms is a sure indication that great amplitude of vibration has been built. up by substantially non-interfering cooperation of all of the forces acting in and upon all parts of the vibratory system.

In assembling the parts the holding bolts 27 are tightened up until the diaphragms are sprung slightly inwardly between the edge and center. They usually bulge out at the center because of the contact with the plunger. The adjusting screws 15 can be turned to regulate the sound of both diaphragms, usually to'tone it down. All the sound is obtained .by the vibration of the diaphragms alone and it is not interfered with by any tapping of the plunger upon them. This I find to be a material improvement over the art in which it was supposed that the sharp impact of a striker on the diaphragm was needed to cause a loud sound.

It will be observed that the operative parts are reduced to an exceedingly simple arrangement. The plunger has no springs connected to it, no pivoted parts are used, and there are no jointed connections of any kind. Furthermore, the plunger always acts axially and 'cannot get out of alinement or into any inoperative position.

Although I have'illustrated and described only one form of the invention, I am aware of the fact that many modifications can be made therein by any person skilled in the art without departing from the scope of the invention as expressed in the claims. Therefore I do not wish to be limited to all the details of construction herein shown and described, but what I do claim is- 1. A sound producer comprising a pair of parallel diaphragms, a plunger between them in contact with both, means for holding said diaphragms in such position that they bulge outwardly at the center and at thev edge and are concave on their outer surfaces at points between.

2. A sound producer comprising a pair of parallel diaphragms, a plunger between them in contact with both, means for moving said plunger in one .direction toward one diaphragm, said diaphragm constituting the sole means for moving the plunger and the other diaphragm in the other direction.

3. A sound producer comprising a pair of parallel diaphragms, a plunger between them in contact with both but unattached to either, means for moving said plunger in one direction toward one diaphragm, the other diaphragm being arranged to move simultaneously in the same direction.

4. In a sound producer, the comb nation of a resilient sound producing element, a floating vibrator movable toward and from the same, means for drawing the vibrator toward said element far enough to flex it and then releasing the vibrator, said element constituting the sole means for forcing the vibrator in the opposite direction by its recoil, and a second resilient sound producing element spaced from the first one and located in position to be vibrated by said vibrator when moved under the influence of the first named element.

5. In a horn, two parallel similar diaphragms and a plunger between and perpendicular to both of them, said diaphragms being initially sprung outwardly at the ceni ger by said plunger acting as a thrust meni- 6. In a horn, two parallel similar diaphragms and a plunger between and perpendicular to both of them, said diaphragms being peripherally sprung inward toward each other and at the center, initially sprung in the opposite direction by said plunger acting as a thrust member.

In testimony whereof I have hereunto affixed my signature.

JOHN H. XVHEELOGK. 

